Striking bar

ABSTRACT

A striking bar of a type utilized in a percussive tool such as a hammer rock drill, and more particularly a striking bar assembly having improved passageway means therein for providing lubricating fluid intermediate the striking bar and the encompassing supporting bushings.

United States Patent Bailey et al.

STRIKING BAR Inventors: Edward A. Bailey, R.F.D. N0. 2,

Box 37, Newport, NH. 03773; James F. Ordway, 1O Floyd Ave., West Lebanon, N.1-l. 03784 Filed: Mar. 31, 1972 Appl. N0.: 240,170

US. Cl 173/105, 173/D1G. 3, 184/6, 279/193, 279/20 Int. Cl E21b 1/00, B25d 17/20 Field of Search 173/80, 104-109, 173/132, 133, 111; 308/238; 184/6, 6.11; 287/53 SS References Cited UNITED STATES PATENTS 5/1972 Beaumont 173/105 1 Mar. 19, 1974 Caldwell 287/53 SS Holman et al7 173/133 Primary Examiner-Ernest R. Purser Assistant ExaminerWilliam F. Pate. Ill

[ 5 ABSTRACT 12 Claims, 4 Drawing Figures I034 32 2a 26 30 "*1 r/6 PPR \2\ 1\ \l\1\ W lr I 20 1 I? I I v A :J 1 i I I PAIENTED "AR 1 9 I974 SHEET 1 8F 2 srRikiNc BAR Some common striking bars of a type utilized in percussively actuated rock drill assemblies include an elongated generally cylindrical member which comprises: a striking end portion supported in a chuck bushing; a splined or lugged portion adapted to be in driving engagement with a known chuck driver gear; a threaded portion axially spaced from the splined portion and adapted to be coupled to a length of drill steel; and a bearing portion axially intermediate the splined portion and the threaded portion and which is rotatably supported with a support bushing.

In operation of a striking bar of a type described hereinabove there is relative axial and rotative movement between the striking bar and the adjacent supporting and driving elements thereby resulting in the occurrence of rubbing friction. Forces from three primary sources are acting simultaneously on the striking bar. Such sources include: a cyclic axial force resulting from the hammer impacting on the end of the striking bar; a torque load delivered through the splines to the threaded steel; and cyclic bending loads caused by drill steel alignment and whip. As a result of these loads, cyclic temperatures are generated at the rubbing surfaces of the striking bar often causing heat cracking or friction welding in the bearing areas of the striking bar.

By means of the present invention which includes passageway means to deliver cooling and lubricating fluid to the peripheral surfaces intermediate the bearing portions of the striking bar and bushings therefor, the hereinabove mentioned problem of heat cracking on friction welding is greatly reduced.

These and other objects and advantages of the present invention will become more readily apparent from a reading of the following description and drawings in which:

FIG. 1 is a striking bar assembly constructed according to the principles of the present invention;

FIG. 2 is a cross section taken on lines 22 of FIG.

FIG. 3 is a cross section taken on lines 3 3 of FIG. 1; and

FIG. 4 is a cross section taken on lines 44 of FIG. 1.

An elongated generally cylindrical striking bar is of a type utilized in percussively actuated rock drill assemblies (not shown) wherein the rearward end thereof is periodically struck by a reciprocating hammer member and the forward end thereof is adapted to be coupled to a drill string (not shown). For a detailed description of a rock drill assembly of a type than can utilize a striking bar 10 of this invention reference is hereby made to a copending Application Ser. No. 52,290, filed July 29,1970 and assigned to the same assignee as this invention.

For purposes of the hereinabove and hereinafter set forth description, forward and rearward shall refer respectively to the right and left of striking bar 10 as viewed in FIG. 1.

Striking bar 10 comprises: a rear bearing portion 14; a splined or lugged portion 16 forwardly adjacent portion l4;'a forward bearing portion 18 located forwardly adjacent portion 16; and a threaded portion 20 forwardly adjacent portion 18. Portions 14, 16, 18 and 20 are all coaxial with respect to the longitudinal axis X-X of striking bar 10.

The general configuration and utilization of striking bar 10 is similar to the striking bar illustrated and described in a copending application Ser. No. 92,033, filed Nov. 23, 1970 and assigned to the same assignee as is this invention. Accordingly, for a more detailed description of the general configuration and utilization of striking bar 10 reference is hereby made to such copending application; however, a detailed description of the portions of striking bar 10 which relate to the invention hereof will be set forth hereinafter.

Striking bar 10 is rotatably supported by an elongated driving and support assembly 24. Assembly 24 includes a longitudinally extending bore 26 therethrough and the striking bar 10 extends axially through bore 26 in the supported position thereof. Support assembly 24 comprises: forward and rear bushing members 28 and 30 respectively; and a chuck driver member 32 located intermediate members 28 and 30. Members 30 and 28 encompass and rotatably support respective portions of bearing portions 14 and 18. Driver member 32 includes a plurality of circumferentially spaced splines 34 which extend radially inwardly from the inner periphery thereof and which cooperate with splines 36 which extend radially outwardly from the outer periphery of driver portion 16 for the rotatable driving of striking bar 10. Driver member 32 is driven in any suitable manner for example as illustrated and described in the aforementioned copending application Ser. No. 52,290.

in operation of a striking bar 10 as described hereinabove there is relative axial and rotative movement between the striking bar 10 and the support assembly 24, thereby resulting in the occurrence of rubbing friction. Forces from three primary sources are acting simultaneously on the striking bar. Such sources include: a cyclic axial force resulting from the hammer impacting on the end of bearing portion14; a torque load delivered through the splines 34 and 36; and cyclic bending loads caused by drill steel alignment and whip. As a result of these loads, cyclic temperatures are generated at the rubbing surfaces of the striking bar 10 and support assembly 24, often causing heat cracking or friction welding in the respective bearing areas. To alleviate this situation, passageway means 38 is provided which extends continuously along the axial extent of and adjacent the outer periphery of the striking bar 10 to permit a controlled flow of coolingand lubricant fluid to respective bearing surfaces.

Passageway means 38 comprise forward, rear and intermediate communicating portions; 40, 42 and 44, respectively. Portion 42 includes a plurality of circumferentially spaced axially extending grooves 46 which are depressed radially inwardly from the outermost periphery of rear bearing portion 14. Portion 40 is comprised of a plurality of radially outwardly extending circumferentially spaced grooves 48 which extend axially along forward bushing member 28. The minor diameter of the driver portion 16 splines are undercut to a depth greater than the minor diameter of known striking bars thereby providing passageway portion 44 between the minor diameter of portion 16 and the minor diameter of driver member 32.

Lubricating and cooling fluid enters passageway means 38 in any suitable manner, for example oil is injected into the power air stream flowing to the rock drill by means of a lubricator (not shown). The lubricator drizzles oil into the air stream which oil is atomized by the velocity of air being supplied to the rock drill. The oil laden air is introduced into the yoke of the rock drill from two sources. First, leakage of air is allowed around the stem of the piston and into the gear case; both on the outside around the buffer ring and around the blow tube. Second, air is allowed to leak into the yoke from the air motor. These two sources provided air to lubricatethe front end, gears, bearings, and the like. Since the oil laden air must escape or build up pressure such air stream enters passageway means 38 and is discharged therefrom adjacent the forward end thereof. The description hereinabove which makes reference to parts of a rock drill not illustrated in the drawings hereof are well known in the art and for a description and showing of such parts reference is made to the hereinabove mentioned copending application Ser. No. 52,290.

The lubricating and cooling fluid enters passageway means 38 adjacent the rearward end thereof and also through intermediate ports 50 and 52. Ports 50 include a plurality of radially inwardly extending through bores (only one of which is shown) intermediate the axial ends of rear bushing member 30. Ports 52 include a plurality of radially extending through slots (only one of which is shown) adjacent the rearward end of chuck driver member 30.

Inasmuch as the invention herein resides in having a passageway means extending continuously along the axial extent and adjacent the periphery of the striking bar various modifications can be made to the embodiment described hereinabove, without departing from the scope of the invention, for example: the major diameter of drive member 32 can be ofa reduced depth rather than the minor diameter of driver. portion 16; both the major diameter of driver member 32 and the minor diameter 16 can be of reduced depths; the grooves comprising passageway means portions 42 and 40 can be in adjacent members rather than as indicated; and the like.

What is claimed is:

ii. A striking bar assembly comprising: a striking bar member including forward and rear bearing portions with a chuck driver portion disposed therebetween; forward and rear bushing members having contact areas which rotatably support said striking bar adjacent said forward and rear bearing portions, respectively; a chuck driver member in driving engagement with said chuck driver portion and disposed intermediate said bushing members; passageway means extending continuously along the axial extent of and adjacent the outer periphery of at least a portion of said striking bar; at least one of said bearing portions includes at least one axially elongated radially inwardly extending groove and a portion of said passageway means is defined by said groove and the inner periphery of the respective bushing member adjacent thereto; and said passageway means having a cross section to provide a flow' of a fluid therethrough at a rate to cool and lubricate said contact areas.

2. A striking bar assembly as specified in claim 1 including a plurality of said grooves circumferentially spaced about said one of said bearing portions.

3. A striking bar assembly as specified in claim 1 wherein said passageway means extend continuously along the axial extent of and adjacent the outer periphery of said striking bar from the forward end of said forward bushing member to the rearward end of said rear bushing member.

4. A striking bar assembly as specified in claim 1 wherein said passageway means isdefined intermediate the outer periphery of said portions and the inner periphery of said bushing members and said driver member. I

5. A striking bar assembly as specified in claim 1 wherein said driving engagement is between cooperating splines respectively carried by said driver portion and said driver member.

6. A striking bar assembly as specified in claim 5 wherein the minor diameter of the driver portion splines are undercut t0 define a portion of said passageway means intermediate the minor diameter of said driver portion splines and the minor diameter of the driver member splines.

7. A striking bar assembly comprising: a striking bar member including forward and rear bearing portions with a chuck driver portion disposed therebetween; forward and rear bushing members having contact areas which rotatably support said striking bar adjacent said forward and rear bearing portions, respectively; a chuck driver member in driving engagement with said chuck driver portion and disposed intermediate said bushing members; passageway means extending continuously along the axial extent of and adjacent the outer periphery of at least a portion of said striking bar; at least one of said bushing members includes at least one axially elongated radially outwardly extending groove and a portion of said passageway means is defined by said groove and the outer periphery of the respective bearing portion adjacent thereto and said passageway means having a cross section to provide a flow ofa fluid therethrough at a rate to cool and lubricate said contact areas.

8. A striking bar as specified in claim 7 including a plurality of said grooves circumferentially spaced about said one of said bushing members.

9. A striking bar assembly as specified in claim 7 wherein said passageway means extend continuously along the axial extent of and adjacent the outer periphery of said striking bar from the forward end of said forward bushing member to the rearward end of said rear bushing member.

10. A striking bar assembly as specified in claim 7 wherein said passageway means are defined intermediate the outer periphery of said portions and the-inner periphery of said bushing members and said driver member.

11. A striking bar assembly as specified in claim 7 wherein said driving engagement is between cooperating splines respectively carried by said driver portion and said driver member.

12. A striking bar assembly as specified in claim 11 wherein the minor diameter of the driver portion splines are undercut to define a portion of said passageway means intermediate the minor diameter of said driver portion splines and the minor diameter of the driver member splines. 

1. A striking bar assembly comprising: a striking bar member including forward and rear bearing portions with a chuck driver portion disposed therebetween; forward and rear bushing members having contact areas which rotatably support said striking bar adjacent said forward and rear bearing portions, respectively; a chuck driver member in driving engagement with said chuck driver portion and disposed intermediate said bushing members; passageway means extending continuously along the axial extent of and adjacent the outer periphery of at least a portion of said striking bar; at least one of said bearing portions includes at least one axially elongated radially inwardly extending groove and a portion of said passageway means is defined by said groove and the inner periphery of the respective bushing member adjacent thereto; and said passageway means having a cross section to provide a flow of a fluid therethrough at a rate to cool and lubricate said contact areas.
 2. A striking bar assembly as specified in claim 1 including a plurality of said grooves circumferentially spaced about said one of said bearing portions.
 3. A striking bar assembly as specified in claim 1 wherein said passageway means extend continuously along the axial extent of and adjacent the outer periphery of said striking bar from the forward end of said forward bushing member to the rearward end of said rear bushing member.
 4. A striking bar assembly as specified in claim 1 wherein said passageway means are defined intermediate the outer periphery of said portions and the inner periphery of said bushing members and said driver member.
 5. A striking bar assembly as specified in claim 1 wherein said driving engagement is between cooperating splines respectively carried by said driver portion and said driver member.
 6. A striking bar assembly as specified in claim 5 wherein the minor diameter of the driver portion splines are undercut to define a portion of said passageway means intermediate the minor diameter of said driver portion splines and the minor diameter of the driver member splines.
 7. A striking bar assembly comprising: a striking bar member including forward and rear bearing portions with a chuck driver portion disposed therebetween: forward and rear bushing members having contact areas which rotatably support said striking bar adjacent said forward and rear bearing portions, respectively; a chuck driVer member in driving engagement with said chuck driver portion and disposed intermediate said bushing members; passageway means extending continuously along the axial extent of and adjacent the outer periphery of at least a portion of said striking bar; at least one of said bushing members includes at least one axially elongated radially outwardly extending groove and a portion of said passageway means is defined by said groove and the outer periphery of the respective bearing portion adjacent thereto and said passageway means having a cross section to provide a flow of a fluid therethrough at a rate to cool and lubricate said contact areas.
 8. A striking bar as specified in claim 7 including a plurality of said grooves circumferentially spaced about said one of said bushing members.
 9. A striking bar assembly as specified in claim 7 wherein said passageway means extend continuously along the axial extent of and adjacent the outer periphery of said striking bar from the forward end of said forward bushing member to the rearward end of said rear bushing member.
 10. A striking bar assembly as specified in claim 7 wherein said passageway means are defined intermediate the outer periphery of said portions and the inner periphery of said bushing members and said driver member.
 11. A striking bar assembly as specified in claim 7 wherein said driving engagement is between cooperating splines respectively carried by said driver portion and said driver member.
 12. A striking bar assembly as specified in claim 11 wherein the minor diameter of the driver portion splines are undercut to define a portion of said passageway means intermediate the minor diameter of said driver portion splines and the minor diameter of the driver member splines. 